This invention relates to electroluminescent lamps.
Electroluminescent lamps are typically formed of a phosphor particle-containing layer disposed between corresponding wide area electrodes, adapted to apply an excitation potential across the phosphor particles. A barrier against moisture penetration, in the form of a film, is bonded to the electrodes that form the exterior of the lamp to prevent premature deterioration of the phosphors due to moisture intrusion.
It has been known to form the semi-transparent front electrode of such prior art lamps of particles of conductive material such as indium oxide or silver dispersed in a binder material. The selection of conductive materials suitable for use in the light transmissive front electrode is limited by the requirement of electrical conductivity, and the desire for the maximum transmissivity of available light. Aesthetics are also a consideration, it being desirable for an electroluminescent lamp, used, e.g., in an automobile, to have a consistent color, typically white, whether the lamp is on or off. In typical prior art lamps, it has been necessary to employ non-conductive, diffuse covering layers to achieve the desired color in the "off" mode, with resultant diminished brightness of the electroluminescent lamp in the "on" mode.